Pastor Rick Warren talked about politics and religion in light of the school shooting in Newtown, Conn., in an interview on "Fox News Sunday." He also discussed his new book written for young adults.

"With the two Sandys -- Sandy Hook and Hurricane Sandy -- we really need the Christmas spirit right now," said Warren, senior pastor of Saddleback Church in Lake Forest, Calif.

The most immediate need, he continued, is to help those who are grieving. Grief is a good thing, because, "it's the way we make transitions in the losses of life." It's important, therefore, not to "stuff our grief."

"Jesus said, 'blessed are those who mourn, they shall be comforted.' If we stuff our grief, I've figured out, it comes out sideways later on in some strange ways. Part of the healing process is actually dealing with the grief," Warren said.

Warren advised helping people dealing with grief just by being with them and loving them.

"You don't have to say anything, you don't need anything profound, you don't need to be wise. You just need to sit with people and love them during their grief," he said.

As far as dealing with the long-term issues related to the recent string of mass shootings, Warren argued changes are needed with regard to mental illness, assault weapons and video games.

"There's a mental health angle that you have to deal with, I don't think we're taking care of those struggling with mental illness like we need to in America. There is the civil safety issue, which is gun control and these assault weapons -- they don't call them 'assault weapons' for nothing. There is the social issue ... students, by the time they're 18, they've maybe killed 10,000, 20,000 people on video games without any remorse for it. It creates a culture of violence."

At the deepest level, though, Warren said the "emptiness inside of people that causes people to be enraged like this," is the most important one to deal with: "When we don't have peace in our hearts, we're not going to have peace with each other."

A revised version of Warren's best-selling book, The Purpose Driven Life, was recently published. The new version has a new subtitle, What on Earth Am I Here For.

For the updated version, Warren explained that he wanted to speak to the many young adults today who feel like their life is in limbo due to the sour economy. He hears from many in that age group, Warren said, who have finished college, do not have a job and have moved back in with their parents.

They "are pretty disillusioned with the American dream," and he wanted to "help them find some meaning and purpose while we're waiting on the economy to turn around."

When asked about President Obama, Warren said his biggest disappointment is the disunity in the nation.

"President Obama ran saying he was going to be a unifier and our nation is more divided than ever before. I think it's more divided than at any time since the Civil War; that's disheartening to me."

Warren clarified, though, that he does not only blame the president. "There's plenty of blame to go around," and he would like to see politicians blame each other less.